Polyethers co-initiated by sucrose and sorbitol and urethane resins therefrom



United States Patent Ofiice 3,369,014 Patented Feb. 13, 1968 3,369,014POLYETHERS CO-INITIATEI) BY SUCRGSE AND SORBITOL AND URETHANE RESINSTHEREFROM Robert E. Booth, Syracuse, N.Y., assignor to Allied ChemicalCorporation, New York, N.Y., a corporation of New York No Drawing.Continuation-impart of application Ser. No. 286,523, June 10, 1963. Thisapplication Sept. 13, 1966, Ser. No. 578,960

2 Claims. (Cl. 260-209) ABSTRACT OF THE DISCLOSURE The present inventionrelates to novel polyether compositions and methods for preparing themwherein the polyethers are characterized by a hydroxyl number of 350 and600 and are prepared by reacting propylene oxide with a mixture ofsucrose and sorbitol, wherein the ratio of sucrose to sorbitol in thereaction mixture is in the range of 0.5 to 2 mols sucrose per mol ofsorbitol, at a temperature within the range of 100 to 110 C. andcontinuing the introduction of the propylene oxide into the mixture ofsucrose and sorbitol while maintaining the temperature of the mixturebetween 90 C. and 110 C. until the hydroxyl number of the polyetherreaction product is in the range of 350 to 600.

This application is a continuation-in-part of application Ser. No.286,523 filed June 10, 1963, now abandoned.

Sucrose, because of its inherent structure namely eight hydroxyl groupsper molecule, i.e. high functionality, and its availability in highlypurified form at low cost, would appear to be a good initiator for theproduction of polyethers for use in the manufacture of rigid foam. Infact, however, sucrose polyether prepared by reaction of sucrose withpropylene oxide when used alone in foam formulations with diisocyanateresults in an unsatisfactory rigid foam, because of its extremelybrittle and powdering characteristics. The use of sucrose as aninitiator involves further complications.

More specifically, the literature mentions a melting point for sucroseof 186 C., but it is not a true melting point in the sense that a singlesample of the subject material will melt and freeze repeatedly as itstemperature is raised or lowered past this point. Sucrose melts onlywith decomposition, evidenced by severe darkening, even charring, andthe melt will not freeze upon cooling to the original crystalline formof sucrose. Molten sucrose cools to a caramel-like substance that can beshown by chemical examination to be a mixture of many carbohydratematerials and decomposition products. This caramel has a high content ofaldose sugars, characterized by an internal cyclic acetal structure,formed by cleavage of the original larger sucrose molecule. Thisstructure interferes with the addition of propylene oxide, even tohydroxyl groups elsewhere in the molecule whereone would expect it toadd. This is easily shown in the case of pure aldose sugars, forexample, glucose.

In an effort to overcome the aforementioned problem, inert liquidmediums have been suggested for incorporation with the sucrose but thesenot only reduced the capacity but also created another problem involvingseparation of the inert material from the resultant polyether. Inanother attempt water Was added to the sucrose to form an aqueoussucrose solution and into this solution propylene oxide was introducedto form the polyether. The presence of water however lowers thefunctionality, i.e. number of hydroxyl groups per molecule in theresultant product, because the polyether derived from reaction of waterwith propylene oxide has a functionality of 2, thus reducing the averagefunctionality of the product (sucrose has a functionality of eight, i.e.there are eight hydroxyl groups per molecule). High functionality is important because good dimensional stability of rigid urethane foam(freedom from swelling under hot and/ or humid conditions) is demandedby the industry and improves with increased functionality of thepolyether.

An object of the present invention is to provide a polyether compositionhaving a high functionality of at least 7 eminently suitable forproducing rigid foams with excellent dimensional stability. Anotherobject is to provide a novel method for preparing a polyethercomposition of high functionality of at least 7 in which sucrose is areactant. A further object is to provide rigid cellular urethanes ofgood dimensional stability by reaction of organic polyisocyanates withthe polyethers of high functionality. Other objects and advantages willbe apparent from the following description.

In accordance with the present invention a polyether composition of highfunctionality may be prepared by introducing propylene oxide into amixture of sucrose and sorbitol at a temperature within the range of100-120 0., preferably 100-110 C., continuing introduction of propyleneoxide into said mixture of sucrose and sorbitol while maintaining thetemperature of said mixture between and 120 C. preferably ll0 C. toeffect reaction of the propylene oxide with the sucrose and sorbitoluntil the hydroxyl number of said polyether reaction composition is inthe range of 350 to600, preferably 450 to 500, said sucrose and sorbitolin the reaction mixture being in the proportion of 0.5 to 2 mols sucroseper mol of sorbitol preferably 0.75 to 1.4 mols sucrose per mol ofsorbitol, and discontinuing the introduction of propylene oxide when thepolyether composition reaction product has reached a hydroxyl numberwithin the desired range of 350 to 600. The polyether composition is anormally liquid .product of high functionality in excess of 7 and uponreaction with diisocyanate formulation for producing foam results in arigid foam of excellent dimensional stability.

The preparation of the polyether composition of the present inventionmay be conveniently carried out by introducing the sorbitol and sucroseinitiators into a reaction vessel equipped with a suitable mechanicalstirrer to insure dispersion of the sucrose throughout the body ofsorbitol. The initiators are then heated to a minimum temperature of C.Initial temperatures below 100 C. should be avoided because ofdifficulties in operation. Propylene oxide is then introduced into thebody of sorbitol and sucrose wherein it reacts with the hydroxyl groupsof the sorbitol and sucrose to form polyethers. Later, when initiation(addition of propylene oxide) is well under way, i.e. about 20% or moreof the propylene oxide reacted, low temperatures e.g. 80 C. arepermissible. Temperatures below 80 C. should not be employed because ofuneconomic reaction rates. Temperatures substantially above C. should beavoided because such highertemperatures cause deeper colored productsdue to sucrose decomposition.

The operation may be conducted at atmospheric, superatmospheric orsubatmospheric pressure but for convenience and economy is conductedunder substantially atmospheric pressure or low pressures such as about1 to 20 p.s.i.g. The reactants need not be introduced into the reactionvessel simultaneously but if desired the sorbitol may be firstintroduced into the reaction vessel, heated to 100 C. and then sucrosegradually added while simultaneously introducing propylene oxide. Theproportion of sucrose to sorbitol is important for the reason that aratio greater than 2 mols sucrose per mol of sorbitol results inunmanageable viscosity difliculties in the operation and ratios below0.5 mol of sucrose .per mol of sorbitol give a polyether compositionwhich when reacted with isocyanate formulations for production of rigidfoam produce a foam having excessive primary shrinkage and poordimensional stability. Consequently the ratio of sucrose to sorbitolshould be within the range of 0.5 to 2 mols sucrose preferably 0.75 to1.4 mols per mol of sorbitol. Another factor of importance in obtaininga good polyether composition for production of stable foam is thehydroxyl number which should be within the range of -0 to 600 preferably450 to 500. This can be readily controlled by regulating the amount ofpropylene oxide introduced into the sucrose-sorbitol mixture. Thereaction of the propylene oxide with the mixture of sucrose and sorbitolis carried out inthe presence of a small amount generally less than 1%,usually about onetenth to five-tenths percent by weight of the reactantsof an alkali metal hydroxide preferably potassium hydroxide. The alkalimetal hydroxide catalyst is preferably added in solid form but may alsobe added as an aqueous solution. Although minor amounts of water i.e. anamount less than onehalf percent preferably less than one-quarter of apercent by weight of the polyether composition may be incorporated inthe reaction mixture, amounts of water ,in excess of this quantityshould be avoided as it materially affects the functionality of theresultant product.

Rigid foams are prepared by reacting an aromatic isocyanate with thepolyether composition of the present invention in the presence ofvarious adjuvants such as blowing agents, activators or catalysts, aciddispersing agents or emulsifiers as is now conventional practice. Thefoams can be made by the one-shot technique using either a volatilefluorocarbon or carbon dioxide generated by the reaction of water withdiisocyanate as the blowing agent. The foams can also be produced by thequasi prepolymer technique wherein a quasi prepolymer is first preparedby reaction of isocyanate with a portion of the polyether and this quasiprepolymer subsequently admixed with additional polyether and adjuvantsto form the foam.

A wide variety of polyisocyanates and prepolymers thereof may be used inpreparing the cellular urethanes of our invention. Liquid organicpolyisocyanates and especially liquid aromatic diisocyanates arepreferred. Among examples of suitable polyisocyanates are the following:

m-phenylene diisocyanate 2,4-tolylene diisocyanate 2,6-tolylenediisocyanate napthalene-l,S-diisocyanate methylene-b is(4-cyclohexylisocyanate) methylene-bis(4-phenylisocyanate)1,6-hexamehylene diisocyanate 4,4',4"-tripl1enylmethane triisocyanate1,3,5-benzene tn'isocyanate Mixtures of the above polyisocyanates andequivalent compounds or compositions may also be used in my invention.

Suitable blowing agents are well-known in the art, but I prefer to use alow-boiling fluorinated aliphatic saturated hydrocarbon. Examples ofthese blowing agents include:

trichloromonofluoromethane dichlorodifluoromethanemonochlorotrifiuoromethane dichlorotetrafiuoroethanetetrachlorodifiuoroethane 1,1-difluoroethane1,1,1-monochlorodifluoroethane Mixtures of these compounds andequivalent compounds may also be used in my invention.

The blowing agents are characterized by being liquids or gases at normaltemperatures and pressures, having poor solvent power for the organicpolymer and boiling at or below temperatures generated by thepolymerization reaction, usually not in excess of about C. The agentspreferably have significant solubility in the polyisocyanate componentand, when in the gaseous state, have a molecular size such that they donot diffuse readily through the interstices of the polymer molecules atambient temperatures. The amount of blowing agent may vary from about 2%up to 40% or more by weight of the polyether.

The catalyst, accelerator or activator is used to promote or otherwiseregulate the reaction between the polyisocyanate and the polyether.Tertiary amines such as triethylamine, dimethylethanolamine, pyridine,quinoline, N-alkyl morpholines and the like are conventionally used. Tinsalts such as dibutyl tin dilaurate, tributyl tin octanoate,bis-(2-ethylhexyl)tin oxide, dibutyl tin dichloride, tin hexanoate,stannous octoate and the like may be used alone or in conjunction withthe above-described tertiary amines. The amount of catalyst used mayratlge from about 2 to 12 percent or more by weight based on the weightof the polyether. The catalyst can be introduced at any desired timealthough it is generally added to the polyether component prior toreaction thereof with the polyisocyanate component.

If desired, emulsifying agents may be used to improve the intermixing ofthe polyether and polyisocyanate components which are usually mutuallyinsoluble. The polymerization reaction may be assisted by vigorousagitation and also by use of these emulsifying agents. Any of a numberof known emulsifying agents can be used. I prefer, however, to employsiloxane-oxyalkylene block copolymers which have the general formula inwhich R, R and R" are C alkyl radicals, p, q and r are integers rangingfrom 2 to 15 and (C H O) is a polyalkylene block which is preferably apolyoxyethylene-polyoxypropylene block containing from 10 to 50 of eachoxyalkylene unit. These siloxane-oxyalkylene block polymers arecommercially available, one such being marketed under the tradedesignation Silicone L-520 in which, referring to the general formulaabove, R=CH R'=C H R =C4Hg, p, q and r=7 and the block (C H O) is apolyoxyethylene-polyoxypropylene block containing 50 units of eachoxyalkylene moiety. Other emulsifying agents suitable for use in theinvention include polyethylene phenol ether, blends of polyalcoholcarboxylic acid ester, oil-soluble sulfonates and the like.

If desired, the flame retardency of the cellular urethane products ofthis invention can be implemented by use of known flame retardantagents. Such agents, as is known, may or may not contain groups whichare reactive with .polyisocyanates. In the former instance, the amountof polyisocyanate used should be adjusted to accommodate the reactivegroup. Representative of these fire retardants are:

(l) Non-reactive agents:

antimony trioxide tris( chloro ethyl phosphatetris(2,3-dichloropropyl)phosphate tris(2,3-dibromopropyl) phosphate bis(beta chloroethyl)vinyl phosphate (2) Reactive agents:

chlorinated diphenol Z-hydroxyethyl phosphite The polymerizationingredients and additives can be mixed in various ways depending uponthe type product desired. Generally the polyether together withcatalyst,

emulsifying agent and other adjuvants are premixed and then addedtogether with a solution of the polyisocyanate and blowing agent to amixing apparatus. The amount of polyether and polyisocyanate employedmay vary over a wide range. Preferably the polyether is reacted with anamount in excess of an equimolar quantity of the polyisocyanate. Ifdesired, the blowing agent can be introduced into the premix rather thanthe polyisocyanate. Further, the polyisocyanate can be prereacted with aportion of the polyether to form a quasi prepolymer: The latter is addedto a premix comprising the balance of the polyether and other adjuvants.The mixture is thoroughly agitated, preferably at room temperature, toinsure the blending of the reactants and is then poured or otherwiseintroduced into a suitable mold and permitted to form freely therein.The foam is then allowed to set at ambient temperature or cured byplacing the foam in a heated enclosure for a predetermined perioddependent upon the requirements of the particular system employed.

The follownig examples illustrate the present invention.

EXAMPLE I 3385 g. Sorbitol and 100 g. KOH (catalyst) were meltedtogether in a columnar cyclic reactor. Propylene oxide addition, throughthe bottom of the reactor, was begun at 100 C., providing agitation forthe mixture. Simultaneously, sucrose addition was made through the topof the reactor, 4651 g. sucrose being added over a one-hour period.Addition of propylene oxide was continued at 100 C. until 25,769 g.polyether had been made, using 17,633 g. propylene oxide. The curedpolyether was stripped of volatiles by a nitrogen purge for 1 hour at100 C. The cooled (2530 C.) crude was acidified to a pH of 5.0 with 220ml. 25% aqueous HCl, digested (agitated) 3 hours at 25 C., diluted with2 volumes of acetone, and filtered of precipitated salts.2,6-di-tert-butyl-4-methylphenol (52 g.) was added to the filtratesolution. Acetone was evaporated at 100 C. and reduced pressure, and therecovered polyether was stripped of traces of volatiles by a nitrogenpurge for Analysis:

Hydroxyl Number (mg. KOH/g.) 463 pH 5.4 Water "percent" 0.06 Viscosity(cps. at 25 C.) 78,200 Acid Number (mg. KOH/g.) 0.12

This polyether has 49 equivalent percent octol and 51 equivalent percenthexol, calculated from the weights of sucrose, sorbitol, the total batchand the hydroxyl number. Average functionality: 7.

EXAMPLE II A rigid urethane foam was prepared of this polyether: 120 g.polyether was mixed with 1.2 g. of silicone emulsifier, 0.5 g. dibutyltin dilaurate and 1.2 g. of dimethylethanolamine. When this mixture wascompletely homogeneous, 31.0 g. tn'chloro-fluoromethane was added, andthe mixture again agitated until homogeneous. This mixture was agitatedat 2400 r.p.m., 106.8 g. tolylene diisocyanate was quickly added, andseconds later, the mixture was poured into a 8" x 8" mold. Two minuteslater it had finished rising, giving a rigid foam bun 8" x 8" x 6",which was cured by standing at room temperature 24 hours. Tests on thefoam showed the fol- Primary shrinkageDimensional loss during cure.

Penetration-Scom denotes foams toughness, resistance to compression, andfreedom from friability. Scores of 130 and above are good.

8 Dimensional stabiiityVolume increase (swelling) during test as much as10% is acceptable; 45% is very good.

Several other sucrose-sorbitol co-initiated polyethers, and their foams,were prepared by the above described process. All pertinent data arerecorded in Table I.

Although certain preferred embodiments of the invention have beendisclosed for purposes of illustration it will be evident that variouschanges and modifications may be made therein without departing from thescope two hours at 110 C. 45 and spirit of the invention.

TABLE I Polyether Preparation Analyses Ex. Wt. of Wt. of Wt. of HydroxylOctol: Hexol Viscosity Sucrose Sorbitol Propylene Wt. of KOH No. (mg.Equiv. (cps. at pH (3:1 Water (wt. Acid No. (grams) (grams) (Oxide)(grams) KOH/g.) Ratio 25 C.) MeOH:H2O) percent) (mg. KOH/g.)

grams Foam Formulation, pts. by wt.

Example Polyether Tolylene Silicone Emulsifier Dibutyltin- 'Iriehloro-DMEA Diisocyanate Dilaurate Fluoromethane Foam Properties Prim. Shrink.Appearance Dim. Stab.

Example Density, lbJit. (percent vol. Penetration (percent vol.

decrease) Surface Cell Size Cell Uniform increase) 3 2. 0 0 V. good V.good V. good 4 4 2. 0 0 ..do. Good Good. 130 5 I claim:

1. A polyether composition of high functionality obtained by introducingpropylene oxide into a mixture of sucrose and sorbitol at a temperatureWithin the range of 100-120 C., continuing introduction of propyleneoxide into said mixture of sucrose and sorbitol while maintaining thetemperature of said mixture between 80 and 120 C. to effect reaction ofthe propylene oxide with the sucrose and sorbitol until the hydroxylnumber of said polyether reaction composition is in the range of 350 to600, said sucrose and sorbitol in the reaction mixture being in theproportion of 0.5 to 2 mols sucrose per mol of sorbitol, anddiscontinuing the introduction of propylene oxide when the polyethercomposition reaction product has reached a hydroxyl number within thedesired range of 350 to 600.

2. A polyether composition of high functionality obtained by introducingpropylene oxide into a mixture of sucrose and sorbitol at a temperaturewithin the range of 100-110 C., continuing introduction of propyleneoxide into said mixture of sucrose and sorbitol While maintaining thetemperature of said mixture between 90 and 110 C. to efiect reaction ofthe propylene oxide with the sucrose and sorbitol until the hydroxylnumber of said polyether reaction composition is in the range of 450 to500, said sucrose and sorbitol in the reaction mixture being in theproportion of 0.75 to 1.4 mols sucrose per mol of sorbitol, anddiscontinuing the introduction of propylene oxide when the polyethercomposition reaction product has reached a hydroxyl number within thedesired range of 450 to 500.

References Cited UNITED STATES PATENTS 3,167,538 1/1965 Kaiser et al.260-210 3,169,934 2/1965 Dennett et a1 260-209 3,277,076 10/1966Yotsuzuka et al 260-209 LEWIS GOTTS, Primary Examiner.

I. R. BROWN, Assistant Examiner.

